Rubber compound and method of preserving it



Patented Sept. 15, 1931 v UNITED STATES PATENT oFFicE ALBERT M. CLIFFORD, OF AKRON, OHIO, ASSIGNOR T THE GOODYEAR TIRE & RUBBER GOJSII'ANYQOFQAKRON, OHIO, AQOBPORATIQN OF OHIO I RUBBER comrounn AND Mnrrron or rnnsnavme' I'I.

Application fil ed August 31, 1927; Serial No. 216,780.

No Drawing.

My invention relates to the treatment of rubber and it has, for its primaryobject, the provision of a material which is adapted to be incorporated into a rubber compound for 5' the purpose of arresting the deterioration thereof.

More specifically, the object of the invention is to provide an antioxidant for rubber,

which is composed ofrthe reaction product of a diamine and a naplithyline compound,

such as naphthol. f

By the incorporation of certain amino bodies in a rubber compound, the physical and chemical characteristics of the latter have been'found to be very materially affected. Certain of these compounds are employed as accelerators of the rate of vulcanization of the rubber compound. Another group of the amino substances, when introduced into the rubber, causes a reduction of oxidation or aging of the rubber, and thus greatly prolongs the period of usefulness'of articles manufactured therefronn, n

. I have made the discovery that naphthyline substituted diamines may be employed in a rubber compound as antioxldants. These materials may be prepared by there action of the naphthols, either alpha or beta, with a diamine. Theoretically, the general reaction of these substances is represented as follows:

In the above equationR represents a hydrocarbon residue, either aryl or alkyl, and

7 R and R represent hydrogen atomsorsubstitutes therefor. 1 V r The reaction products of beta naphthol and ethylene diamine arespecific examples of compounds which fall within the scope of 1 my invention. This material maybe manu- E H I d E ,H i i 1'1 H 1 75 E-on 4 HO- Noniomfi l l/re-omoml- +mo factured by the following method. Intermix molecular quantities of beta na and ethylene diamine,or a slight excess of the latter, with one-half mole of anhydrous thendried and maybe obtained as a crystal- 1 line product by crystallization from either alcohol or Xylene The melting point of'the crystalline material ranges from 146 to 148 C.': Thefcrystalli'ne nature ofrthis material and the factthat it has a very definite melting point, are stronglyindicative that it is a true chemical reaction product. The chemical equation of these materials is represented as follows:

The above method is not limited to the 8 specific materials indicated, but is of general application in the preparation of all materials of this class.

My invention is not limited to the reaction products of alkyl diamines and naphthol, but also includes the reaction products of aryl diamines and the naphthols. A specific example of the latterinaterial is the reaction product of. metaphenylene diamine and naphthol. This material maybe prepared by substantially. the same process as that employed in the manufacture of the reaction product 'ofethylene diamine and the beta naphthol. [The material ,thusflobtained is resin-like in appearance and has a melting point of approximately 100 C. This resinlike-substance is believed to consist of two reaction products (metaphenylene diamine derivative of beta naphthol and the mono amine derivative of beta 11a hthol). The reaction between the amino ody and the naphthol may be represented by the following equation:

The materials prepared according to the parts Zinc oxide 5 parts Sulphur 3 parts Stearic acid .1.5 parts Hexaniethylene tetramine 1 part Antioxidant; 1 part Tests conducted upon samples prepared in accordance with theformula clearly show the value of the. materials .as antioxidants. The data obtained from the tests is contained in the appended tables. Tables I and II contain the data obtained from samples" which had not been subjected to artificial aging.

1 Table I Sym. di (beta-naphthylamino) ethane Cure 5.00% 700% Tensile Percent I elong. elong. strength elong. Time in Lbs.per kgs/cm kgs/cin kgs/cm atbreak min. sq. inch 30 40 19 61 126 i 835 50 l 40 27 100 163 795 70 1 40 as 1 143 192 755 Table II M-phenylene diamine derivative of betanapthol Cure 500% 700% Tensile Percent elong. elong. strength e1ong.. Time in Lbs. per kgs/cm kgs/cm kgs/cmat break min. sq. inch Samples were also tested to ascertain their age-resisting properties by subjecting them to a temperature of 50 C. and a pressure of 150 lbs. per square inch in an oxygen bomb for six days. The results obtained are indi cated in tables III and IVappended hereto.

HH+H:Q

, v I T able I I l Sym. di- (beta-naphthylamino) ethane 500% 700% Tensile eipng/g. elpm/g. stiipnglth %gloi;]g\. %wt. gs as at re increase hrusts; m

so 40 2a 71 i 117 800 0.10 50 40 34 118 167 705 0.12 70 4o 152 188 740 I 0.28

.. Table I V I M-phenylene diamine derivative of betanaphthol ure 500% 200% Tensile eiong. eiiong. string/15h %gloni. i%vvt. Timein Lbs'pet g5 g5 g3 at I63 ncrease min. sqdnch cmz cm! v 30 40 05 110 815 0.00 50. 40. t 102 173 800 0.00 70 38 i3? 176 750 0.32

It is evident from the tabulated data that only a very slightly injurious efiect upon the characteristics of the rubber was caused by subjecting the rubber samples to the oxygen bomb test. Indeed it will be observed that the tensile strength in most cases was materially improved after subjection to the art-ificial aging, and that but a slight increase in Weight, clue to the absorption of oxygen, was observed. p C

The chemical formulas which have been given in explanation of the reactions which take place during the process of preparation ofthe. antioxidants are believed to be inaccordance with the generally accepted theories However, the usefulness of my inven .tion' is not'depende-nt upon the correctness of the latter; and consequently the validity of any patents obtained should not be affectejd thereby.

' comprises incorporating a substance having the chemical formula wrrcmonmm into a rubber compound and vulcanizing the mixture.

2. A method of preserving rubber which comprises incorporating dinaphthyl ethylene diamine into a rubber compound and vulcanizing the mixture. 7 I

3. A rubber product which has been vulcanized in the presence of the reaction prodnot of a naphthol and ethylene diamine.

i. A rubber product which has been vulcanized in the presence of dinaphthyl ethylene diamine. a

5. A method 6% preserving rubber which comprises incorporating therein a reaction product of a naphthol with a diamine selected from a group consisting of ethylene diamine and phenylene diamine.

6. A method of preserving rubber which comprises incorporating therein a material having the following formula:

in which R and R are naphthylene groups and R is a radical selected from a group consisting of ethylene and phenylene.

In witness whereof, I have hereunto signed my name.

Signed at Akron, in the county of Summit, and State of Ohio, this 30th day of August, 1927.

' ALBERT M. CLIFFORD. 

